2. Introduction
The history of comet watching dates back to 1000
BC from the Chinese records and Chaldea, a place
in present Iraq.
Comets have been regarded as omen, even as
recently as 1986.
Battle of Hastings - 1066
Today Astronomer study Comets from scientific
perspectives, and our understanding of these
fascinating objects have grown tremendously.
3. Dirty Snowballs
Comets are dusty chunk of ice
During each orbit around the sun they
partially vaporize
Have elliptical Orbits
4. Structure of a Comet
Solar heat vaporizes the
nucleus to produce
Coma - Hydrogen gas
Envelope
Dust tail
Ion tail
5. Orbits of Comets
Elliptical in Shape Aphelion distance
Randomly oriented Comet
Sun
Earth
Perihelion distance
6. Comets Tails
Ludwig Biermann proposed the idea of
solar wind to explain comet tails. Mariner 2
spacecraft captured the one such event in
1962.
7. Comet Tails
The solar wind produces three Comet tails that
point away from the motion of the Comet.
The blue ion tails is ionized atoms of CN and C2.
The dust tail is produced when the photons from the
Sun strike the dust particles and produce radiation
pressure on them. This causes the dust particles to drift
away from the comet.
The effect of solar wind on dust particles is less compared to
that on ions. This gives the dust tails a curved shape.
The third tail is made up of Sodium and is usually
invisible to the unaided eyes.
8. Comet Collisions
Comet collision with Earth can bring devastation
to life on Earth.
Jupiter in our solar system is the largest planet and
thus exerts greater gravitational pull on incoming
Comets.
Study of Shoemaker-Levey collision with Jupiter
gave us important facts about Comet collisions.
